The research is based upon the prospective and continuing study of patients with primary cutaneous malignant melanomas. Approximately 750 cases (May, 1978) form our data base. The long term goals of the project are the reduction of mortality due to malignant melanoma to less than 10 percent and to provide, through the study of melanoma, a model for the general biology of human neoplasia. The specific projects to be studied are: 1. The study of FAMILIAL MELANOMA 2. The relationship between MELANOCYTIC NEVI and malignant melanoma 3. The comparative study of melanomas developing at different ages in life 4. The clinical and histological characteristics of melanomas apparently induced by light 5. The search for virus-like profiles in melanoma cells 6. The study of partial regression of the radial growth phase of primary melanomas, and its relationship to the vertical growth phase 7. The investigation of the characteristics of a primary melanoma which may permit identification of high-risk, low-risk patients on an individual basis. 8. The comparative study of Level II versus Level IV/V primary malignant melanomas 9. A light and electron-microscope study of the MELANOCYTOMAS: Spitz tumors and pigmented spindle cell tumors 10. A clinicopathologic study and fine structural study of certain epidermal MELANOCYTIC DYSPLASIAS.